Commodore 1541 Floppy Drive Hardware Failure Cheat Sheet
See the original scan at the bottom of this page

Commodore Diagnostician II
By Ian Perry, Kyneton, Victoria 3444, Australia   Sept 1989

Symptomatic Chart Diagnosing
Faulty IC Components On
Commodore 1541
Floppy Drive

Error LEB blinks on power upxx
Searching with no red LEDxx
Drive fails to readxxxx
Fails to fomatxx
Stepper motor does not stepxx
Will not save when drive heats upxx
Lights stay on, motor runs continuouslyxx
No LEDs on power upCheck power supply voltage, Check CR3, VR2, VR1, CR1
Drive motor runs continuously with no green LEDCheck 5Volt on power supply
Flashing light on and off Check UC1, UD2
Message of ‘FILE NOT FOUND’ is displayedCheck alignment, defective disk
Drive speed will not stabilizeClean drive head w/ Alcohol, check alignment
Display reads ERROR 21-29 (Disk Errors)Checl PCB speed (LAG570 – for Newt. Drive)
Write protect on ERROR #25Check WPS, UA1, Write Protect Switch, alignment
Track 18 Display 21 read ERRORCheck alignment, UC2, UE6, check R/W head
Will not load certain programsCheck alignment, track 0 stop